Conversion of hydrocarbons



May 4, 1948. H. R. LEGATSKI CONVERSION OF HYDROCARBONS Filed Nov. 5,1945l ATTORNEYS Patented May 4, 1948 CNYESlQN 0F HYDEQQARBQNS, l HaroldIt., Legatskil. Bartlesyilles. Q k a., assignor "le Phillips-Petras@Gsell?,

morele@ n @umanamente 5, 194s sexisme-sasso:

and saturated 1nono-o3rolopar:V

isomerizauon of normal hexane anni meihylcyclonentane. In anotherfaspectthis inyentionjrelates to the preparation of a feed 'composition for anisomerizationplocess.

Natural and straight gaSQlllES.` are. usuglli separated intotheir:variousfV mpnemsby nag; Si

tionai @15u11ation,andthe` comnonenisftnus sep- @rated areutilizedlinvariduswants. Generally, natural and straight run easulines alieseparated into about seven fractions. The lightest fraction comprisespropane and lighterlhydrocarhonsj.

This fraction is further separated into propane which is marketed commerly as liqueefdf'netroleuin gas. The lighter Ydizocarloons `from thisfraction ,may be 'used in; the" production' Qf v carbon black. Thesecond fraction visfa, butarie f fraction icemprislns isobllleue andnormal ,buleue- The tufo ,butenes' are separated and the islebutaee isusually alkyluted with butyleue t0 ferm Otanesx The normal "butahe ismarketedas s lieueued petroleum eee. or may @emprise a leed fel' themanufacture@ butadiene 0r leerte@ used as a gasoline blending agent.- nparitarie fraction is also separatedfrom' the naturalgasoline containingisopentane and normal pantano.

T heisopentane isa blending ingredient for-loth aviation and high octaneniotorf uels. Nornial pentes@ .is es e sulventeusl as blending. @sullaforfrnotor fuels.' A fourth fraction comprising (c1. couette) duction ofa high quality he 'lhe h xane fraction separated from the natur W ugasolnesisofnal? interest sii1e"the isonexanesyhave been afa valuableblending ingredient 'in y t'o isomerizelioth the normal hexane aule o tn tnfiioniiarhesf ne" and' methyloyelopentane w"The Vobject 4ofA this"invention is to isomerize saturatednormal Qarafns and saturated "rjnn'o"-Itffis an object of this' invention tof provide a isoheg'iane andnormal hexanefis separated Yand v the isrohexane fraction `is` 11S ej;lin both'ajliati'on and :noto-r fuels for increasing the, octane qualityof; the product. The normal hexane fraction, which usually contains alarge proportioniof methylcclopentane, is used in rnotor fuels and as asolvent. An isoheptane'fration separated from the natural orstraightrungasolin'is used as a component of 100 octane Agas 'olifrielVStillanother fraction separated from thenatural'and straight rungasoline is'fomp'osed of normal heptane and risooctane This Afrati'on'isfurther's'earated into its components. The normal heptane has varioususes, such as av solvent and as 'a feed forthe manufacture of toluene.Isoocta'xe is Q flins" and Saturated l'noijio-` omerized in a mannerheireprudueel an 'exceptionally c" products" which may be g n agent ier'meh o Q y eneratine theafuref hun frautionflfutu anormal parailuaraillueouueutltateyafid the respective Geneseuis. ef `Whiellarereeelnlined, her duality ,fraction can' be." Qbtalnedthau Quuftheelllnel used as aviation fuel hase stock and inhigh ootanemotor fuel.Usua11y-the1astfractionnog the separati@ ,ef ille naturel ,eed Straight'ruil gasoline comprises norrnal octane and heavier hydrecarbeuswhich.are use@` es .a refqimles. es?.

pnyicycipenijane tossina-t0 @man d. of both c yclohexane andi islohexans"nhasheenjused'das a single blending agent. By separate isomi erizationof the normal heptane concentrate and the methylcyclohexane concentrateultimately a higher quality blending agent can be obtained by combiningthe products of. the separate isomerization reactions than could beobtained by a single isomerization of the original mixture.

The isomerization of the hexanes is carried out under appropriateconditions of temperature,

pressure and residence time known in the art.

Apreferred catalyst comprises a Friedel-Crafts metal halide in the formof a hydrocarbon comweight per cent normal hexane and between about 35and about 20 weight pery cent methylcyclopentane. The normal hexanefraction is separated into a normal hexane concentrate and acycloparaiin concentrate by conventional fractional distillation.Preferably, the normal hexane concentrate contains at least about 85weight per cent and up to about 93 weight per cent normal hexane and thecycloparan concentrate contains at least about 40 weight per centmethylcyclopentane. Each concentrate or fraction is then isomerizedunder appropriate conditions to obtain the desired isomeric product. Inthe case of the normal hexane concentrate, the isomerization product isisohexane; in the case of the methylcyclopentane concentrate, theisomerization product is cyclohexane. In isomerizing the normal hexaneconcentrate it has been found that at least 7 to about 12 weight percent or more methylcyclopentane is desirable to inhibit side reactions,such as disproportionation, dealkylation and cracking. By separatelyisomerizing a concentrated normal hexane fraction and a concentratedmethylcyclopentane fraction the yield of. isohexane and cyclohexane isgreatly increased.

The normal hexane isomerization eiiiuent generally contains more thanabout 55 weight per cent isohexanes and less than about 10 weight percent cycloparafns. 'Ihe methylcyclopentane isomerization ei'liuentgenerally contains more than about 25 weight per cent cyclohexane.

Isohexane is recovered from the normal hexane isomerization effluent asa product of the process and cyclohexane is recovered from themethylcyclopentane isomerization efliuent also as a product of theprocess. If desired these components, isohexane and cyclohexane, or theentire effluents from the respective isomerizations, may be combined toform a motor fuel blending agent. Unconverted methylcyclopentane andnormal hexane from the isomerization eiiiuents may be recycled as aportion of the feed to the respectivelsomerization processes. A portionof the unconverted methylcyclopentane may be added to the feed to thenormal hexane isomerization in order to maintain the naphthenic contentof the feed within the desired limits.

This invention is equally applicable to the isomerization of othermixtures of saturated normal paramns and saturatedmono-cyclohydrocarbons as herein described. For example, a normalheptane fraction containing an appreciable amount ofmethylcyclohexane isfractionated to form a normal heptane concentrate and amethylcyclohexane concentrate. The normal 'heptane concentrate isisomerized under optimumreaction conditions to produce isoheptanes, andthe methylcyclohexane is isomerized under optimum reaction conditions toproduce dimethylcyclopentane. Both products of the separateisomerization reactions are excellent blending Vagents for motor fuels,thus the products arecombined plexor supported on suitable inorganicmaterial.

Theisomerizationofeither the normal hexane concentrate org themethylcyclopentane concentrate may be carried out in either the liquidor vapor phase without departing from the scope of this j invention.Liquid phase isomerization is preferred.

Amongthe solid inorganic catalyst supports suitable in vapor phaseisomerization are the mineral or mineral-like compounds, preferablynearly completely dehydrated, such as the kaolinites, Terrana,Floridin,` pyrophyllite, apophyllite, meerschaum, serpentine, keserite,bentonite, talc, bauxite, the permutites, the zeolites and the like, as'well as the prepared hydrated materials such as the prepared permutitesand zeolites, aluminum oxides, magnesium oxides, silica, and similarcompounds prepared by partial dehydration of the hydroxides and thelike. Y The above materialsV are employed in admixture or in combinationwith an active metal halide isomerization catalyst of the Friedel-Crafts or aluminum halide type. Preferred catalysts are those comprisingaluminum chloride and aluminum bromide.

The catalytic material in any suitable solid form as powder, pillules,pellets, or granules`of the desired size is employed in mannerscustomary in the execution of catalytic processes of this type. Thedesired quantity of the-granular catalyst material may be `packed orotherwise contained ina reaction tube, chamber or tower and maintainedat the desired temperature by suitable heating and/or cooling meanswhile the material to be treated is passed into contact with it underthe appropriate pressure for the required periodl of time. Y 'Vaporphase isomerization, generally, is executed'at a temperature not greaterthan about 450 F. and preferably at temperatures below 325 F. Attemperatures above 450 F. losses of material due toundesirable crackingreactions are prohibitive. T he lower limit of temperature range is setby that temperature at which the desired isomerization will take placeat a/practical rate. Temperatures as low as about 200 F. may be used inlsome cases where pressure is low enough to assure vapor phase operation.A preferred practical loperating range is from about 200 to about 325 F.A

Unless fairly high pressures are used, the catalyst may suffer loss ofactivity because of the sublimation of the metal halide therefrom. Thus,it is preferred to `use pressures from about to about 400 pounds persquareinch gage. In practice theV temperature and pressure are adjustedso that the isomerization reaction is carrietil out in the vapor phase.If the reaction is effected under moderately superatmospheric pressuresoffrom about 25 to about 350 pounds per square .inch gage, practicableconversion of the hexanes to the desired isomeric products can beeffected at relatively lower temperatures than 52,4405?? oli com-pse`under -reaction'condit'ions to `yield the hydrogen halide, may be added-to the system. The amount of hydrogen halide within the -reaction zone`at-any time should hot `be/more than -lO` I'nol per cent for bestI-I'esults The most suitable `contant time -will depend Aupo'ritheparticular catalyst, upon the reaction conditions, and upon the -ieed'usdj The "con-tact `time `is chosen'so that alpracticable conversion isobtained with the minimum Side lreactions. nIn

'isomerization of hexanesinthe `Vapor phase 'at 'temperatures between-200` and I325" F., contact timesf-rom about l to about `22o-minutes areused.

AThe rcatalyst-in vapor 'phase fisomerization,

'after it has 'suffered substantial deactivation 'be- -cause of use inthe process, Acan be restored to 'its initial-activityby Iadditionof analuminum halide. `The reactivation-caribe:effected Without removing thelcatalyst Afrom the. reaction chamerably `afterthe catalyst Ehas"temporarily been *taken lout of use.

The i catalyst `A'employed-"in Sliquidfphase' isomerization i comprisesessentially Afa VFriedel#Crafts 'met-al halide 'which `-W`ill 1form faesludge complex with an oleflnic polymer, Ikerosene, or an--alkyl ate.This hydrocarbonemetal Ahalidefcon'lplex having some free metalhalid'etherein is v"a very active catalyst. The spentsludge may be LWithdrawnVfrom -the reaction chamber-"and disposed A*oil-since itisTelati'velycheap,` or liti may be regenerated for reuse.

LvThe'presence -in `ti-ie reaction 'system Vduring lid-uid'phase-isomerization of la hydrogen halide appears to have a beneficial effectupon the A".l-ife and-activity of the catalyst. -It inthe-rotore,'beneci'al to the reaction -to havelrelativelyfsmall 4amounts "of`hydrogen 'chloride 'added to Atherea'etaits and presn-tduring thereaction.

1I-he pressure ofthe "reaction chamber in? liquid phase isomer-izationis f maintained so -as to :keep the heXanesthe liquidfpha'se in thechamber at fthe 'iisomeiiization temperatures. vPreferred pressures areabout 200 to about 450 pounds pensquarel'inch 'gage. The reactiontemperatures-for lliquid phase isomerizationfares'ome- Whatlowerithanthose temperatures used in vapor` Aphase Yi`somerizatioi'i. The reaction-temperatures Jinay i range 'from about' 100- t'o `about 375`TF.,' and'preferably from? about 11150 tof about 275 l `The v'Contact time of theffeedi'with the -c'atalyst 'lfor lliquid phase lisomri-'Zation "imay`vary Within a relatively large rangeV without :affecting the conversionprocess. Contact ti-'mes from about-2 to 'about`30 minutesa'remostdesirable.

The `reaction chamber Fifor -f liquid phase isomerization may befpacked"Wi-thi'a ysolid. catalyst supporting material or carrierA agent, As'uch1was carbon fRaschig ringsgfof such la nature ras-"to have a highwettability `by the catalyst sludge. The high wettabilityof thesupporting material `assures a large hold-up of the catalyst sludge.This packing material is ordinarily relatively inert with respect toreactants and catalyst. Examples are Raschig rings, Berl saddles, etc.,m-ade from carbon, glazed or unglazed porcelain or other ceramic Wear.Other types of packing which may be used include bauxite, activatedalumina, fullers earth, silica gel which may have adsorptive propertiesenhancing the activity of the sludge catalyst. The reaction for liquidisomerization may contain no supporting material at all, but insteadintimate contact between re- `actants and catalyst is -eiected by meansof stirrers within the reaction chamber itself.

Various other isomerization catalysts may be --used which are suitablefor isomerization of hexanes, such as hydrogenfluoride, borontrifluoride', mixtures of hydrogenlluorde and boron trifluoride, andsulfuric acid. Reaction conditions of isomerization yand the catalystused for the Various isomerization` steps may be altered and variousmodifications Will become4 apparent to those skilled in the `artWithoutdeparting from the scope of this invention.

` Preferably, the normal hexanepconcentrate is isomerized at` atemperaturebetween ,about 210 and about 375 F. and under sufficientpressure to maintain the reactionmixture in theliq-uid phase. Analuminum chloride-hydrocarbon complex containing between about 50 andabout weight per cent aluminum chloride is preferred as the catalyst.The methylcyclopentane 'concentrate is isomerized at a Atemperaturebetween about and 200 F. `under :suicient EXAMPLE i I A normal hexaneVfraction was isomerized without preliminary .fractionation Thefollowing is the approximate :feed and eluent compo,- sitions.

Per ent Pentanes and lighter 4. 8 Isoliexaues 5 52. 9Methylcyclopentane.. 2l 9. 8 Cyclohexane 4 1 7. 2 Normal Hexane v '.7019. 2 Heavier hydrocarbons 6. 1

Normal: hexane conversion =.72 .4% `lsohexane yield -p er normalhexanereacted 94 .1% -Methylcyclope11tane"reacted 53.8% 1 =Cyclohexaneyield, penmetliylcyclopentane .reacted29.8%

. EXAMPLE 1I A normalfhexane concentrate'was prepared by preliminaryfractionation according to this invention and isomerized under optimumreaction conditions for the formation of isohexanes. The following is4the approximate feed and eiuent compositions.

Eluent Feed Composition, Weight Per Cent Corgsgtmn Per Cent Pentanes andlighter 3. 8 Isohexanes 55. 1 Normal hexane 87. 9 26. 3Methylcyclopentane 12. 1 2. 2 Cyclohexane 3. Heavier hydrocarbons 9. 6

n 100. o 10o. o

Normal hexane reacted= 70.1%

Isohexane yield per normal hexane reacted=89.5% Methylcyclopentanereacted=81.9%

Cyclohexane per methylcyclopentane reacted=31% EXAMPLE III Amethylcyclopentane concentrate was prepared by preliminary fractionationaccording to this invention and isomerized under optimum reactionconditions for the formation of cyclo- Normal hexane reacted=l1.9%

Isohexane yield per normal hexane reacted=95% Methylcyclopentanereacted=51.l

Cyelohexane yield per methyleyclopentane reacted=85.4%

The 85 per cent yield of cyclohexane in Example III as compared to a 29per cent and 31 per cent yield in Examples and II, respectively,indicates the desirability of concentrating methylcyclopentane in ahydrocarbon fraction to at least about 40 per cent of the fraction.

EXAMPLE IV Normal hexane substantially free from other hydrocarbons wasisomerized under ,optimum reaction conditions, and the followingcomposition of the eiiiuent was obtained.

Composition of eluent weight per cent Isobutane a 15.3 Isopentane 14.9Normal pentane 1.7 Neohexane 4.1 Other isohexanes 13.1 Normal hexane37.3 Heptanes and heavier 13.6

Conversion normal hexane=62.7%

Isohexane yield per normal hexane reacted=27.4%

Since the highest yield of isohexanes was obtained whenmethylcyclopentane was present in substantial amount in the reactionmixture, it is evident that a methylcyclopentane content of theisomerization feed above about 12 weight per cent is highly desirable toobtain a good yield of isohexanes Example IV adequate illustrates thedegree of disproportionation resulting when relatively pure normalhexane is isomer-ized without the presence of a disproportlonationinhibitor, such as methylcyclopentane or other naphthene.

I claim: Y 1.` A processk for isomerizing a hexane fraction comprisingbetween about 65 and about 80 weight per cent normal hexane and betweenabout 20 and about 35 weight per cent methylcyclopentane which comprisesfractionally distilling said hexane fraction to form a normal hexaneconcentrate comprising between about and about 93 weight per cent normalhexane and a methylcyclopentane concentrate containing at least about 40weight per cent methylcyclopentane, isomerizing said normal hexaneconcentrate at a temperature between about 210 and about 375 F. undersufcient pressure to maintain the reaction mixture in the liquid phaseand in the presence of an aluminum chloride-hydrocarbon complexcontaining between about 50 and about 80 weight per cent aluminumchloride, fractionally distilling aneffluent from said normal hexaneisomerization to separate isohexane and normal hexane, recycling saidnormal hexane to the aforesaid isomerization, simultaneously isomerizingsaid methylcyclopentane concentrate at a temperature between about andabout 200 F. under suilicient pressure to maintain the reaction mixturein the liquid phase and inthe presence of an aluminumchloride-hydrocarbon complex containing between about 10 and about 45weight per cent aluminum chloride, fractionally distillng an eiiuentfrom said methylcyclopentane isomeriaztion to separate cyclohexane andmethylcyclopentane, recycling a portion of said methylcyclopentane tosaid methylcyclopentane isomerization, introducing another portion ofsaid methylcyclopentane into said normal hexane concentrate in an amountsufficient to maintain a naphthenic content therein or at least 7 weightper cent, and combining said isohexane and said cyclohexane as a motorfuel blending agent. Y

2. A process for isomerizing a hexane fraction comprising between about65 and about 80 weight per cent normal hexane and between about 20 andabout 35 weight per cent methylcyclopentane which comprises fractionallydistilling said hexane fraction to form a normal hexane concentratecomprising between about 85 and about 93 weight per cent normal hexaneand a methylcyclopentane concentrate containing at least about 40 weightper cent methylcyclopentane, isomerizing said normal hexane concentrateat a temperature between about 210 and about 375 F. under suflicientpressure to maintain the reaction mixture in the liquid phase, and inthe presence of an aluminum chloride-hydrocarbon complex containingbetween about 50 and about 80 weight per cent aluminum chloride,simultaneously isomerizing said methylcyclopentane concentrate at atemperature between about 100 and about 200 F. under suilcient pressureto maintain the reaction mixture in the liquid phase and in the presenceof an aluminum chloridehydrocarbon complex containing between about 10and about 45 weight lper cent aluminumchloride, and combining effluentsfrom said respective isomerizations. Y 3. A ,process for isomerizing ahexane fraction comprising between about 65 and about 80 weight per centnormal hexane and between about 20 and about 35 weight per centmethyleyclopentane whichv `comprises fractionally dis-- tilling saidhexane fraction to form a normal hexane concentrate comprising betweenabout 85 and about 93 weight per cent normal hexane and amethylcyclopentane concentrate comprising at least about 40 weight percent methylcyclopentane, isomerizing said normal hexane concentrate at atemperature between about 210 and about 375 F. under sufficient pressureto maintain the reaction mixture in the liquid phase, and in thepresence of an aluminum 'chloride-hydrocarbon complex containing betweenabout 50 and about 80 weight per cent aluminum chloride, fractionally.distilling an effluent from said normal hexane isomerization toseparate isohexane and normal hexane, recycling said normal hexane tothe aforesaid isomerization, simultaneously isomerizing saidmethylcy-clopentane concentrate at a temperature between about 100 andabout 200 F. under sufficient pressure to maintain the reaction mixturein the liquid phase and in the presence of an aluminumchloride-hydrocarbon complex containing between about 10 and about 45weight per cent aluminum chloride, fractionally distilling an eluentfrom said methylcyclopentane isomerization to separate cyclohexaneREFERENCES CITED The following references are of record in the tile ofthis patent:

UNITED STATES PATENTS Number Name Date 2,379,749 Ross et al., I July 3,1945 2,382,446 Ross et al., II Aug. 14, 1945 2,394,797 McAllister et al.Feb. 12, 1946 OTHER REFERENCES Journal Amer. Chem. Soc., vol. 61, July1939, pages 1717-1720 (article by Glasebrook and Lovell).

